The present invention relates to systems for covering open-top containers. In a more specific application of the invention, a system for covering a vehicle container, such as a dump truck body, is contemplated.
Some hauling vehicles, such as dump trucks, include open-top containers used for hauling or storing various materials. For example in a typical dump truck application, the dump body is used to haul a variety of a particulate material, such as gravel, aggregate or similar materials. In addition, some hauling vehicles carry organic materials, such as grain or produce.
Depending upon the nature of the material stored within the open-top container, it is often desirable to provide a cover for the container. Of course, rigid covers are well known that may be hinged from one end of the container body. These rigid covers gradually gave way in the industry to flexible tarping systems because the flexible tarp can be easily stowed when a cover is not necessary and is much easier to manipulate than a rigid cover. A variety of tarping systems have been developed depending upon the particular hauling vehicle application. One such tarping system for use with dump trucks is the Easy Pull(copyright) tarping system of Aero Industries, Inc. The Easy Pull(copyright) system includes a flexible tarp that is wound around a spool at one end of the dump bed. A rope attached to the free end of the tarp can be used to unwind the tarpaulin from the roller to span the length of the dump bed.
Tarping systems of this type have had wide usage over a variety of hauling and industrial applications. However, one drawback of the simple tarping system becomes evident when the hauling container is overfilled with material, or the load is heaped within the container. This heaped condition occurs frequently when dirt, for instance, is hauled to or from a work site. Filling the dump bed with as much material as possible reduces the number of hauling trips that must be made, which ultimately decreases the time-to-completion and cost of the job. An overfilled dump bed can be detrimental to the tarpaulin material as the tarp is pulled across the length of the dump bed. As the tarp scrapes across the heaped load, the tarp material can be worn, or even torn, depending upon the contents of the load. In addition, this scraping action can also dislodge material from the dump bed.
The Easy Cover(copyright) tarping system of Aero Industries, Inc., has provided one answer to that problem. The Easy Cover(copyright) tarping system includes a U-shaped frame that is pivotably mounted at its ends to the base of the container body. The horizontal section of the U-shaped bar is attached to the tarp, while the free ends of the vertical elements are pivotably mounted, Thus, the Easy Cover(copyright) tarping system allows the tarp to be manually pulled in a sweeping arc over the contained load without contacting the load. The U-shaped bar has a height that is substantially greater than any anticipated heaped load contained within the dump body. While this approach solves the problem of pulling a tarp over a heaped load, it does have certain drawbacks. For instance, the U-shaped bar must be of substantial length since it must span between the ends of the dump body. In addition, the U-shaped bar is essentially an integral element of the tarp itself, which can make installation somewhat cumbersome.
As a consequence, there remains a need for a cover system for use in covering heaped loads in an open-top container that is less cumbersome and easier to install. The cover system must be able to keep the flexible cover from scraping across the heaped load.
To address these needs, the present invention contemplates a cover system for an open top container, such as a dump truck bed, that is suited for covering heaped loads within the bed. The cover system includes a pair of pivoting load arm assemblies, one mounted on each side of the bed, that are adapted for use with a retractable tarp system. In such a system, a flexible cover, such as a tarpaulin, is wound onto a roller within a tarp housing mounted at one end of the dump bed. The tarp can include a pull rope associated with a leading edge of the tarpxe2x80x94i.e., the edge being drawn from one end of the bed to the other. Preferably, the leading edge of the tarp is attached to a pull bar, to which the rope is then attached. The object of the cover system of the present invention, as particularly accomplished by the pivoting load arm assemblies, is to convey the tarp over a heaped load within the bed with, at most, minimal contact between the tarp/pull bar and the heaped load.
To accomplish this objective, the load arm assemblies each include a pair of telescoping arms, with a lower arm pivotably mounted to an upper rail of the dump bed. The free end of the upper arm of each assembly includes a yoke, or similar structure that is configured to catch or receive the pull bar connected to a retractable tarp as it traverses across the open top of the container or dump bed. In one specific embodiment, the yoke is formed by a pair of arms diverging to form a notch. The notch opening is supported at the level of the edge of the dump bed side boards by a catch projecting generally perpendicular to the yoke. Thus, in its initial position, each load arm assembly is positioned with the yoke facing the tarp housing and the notch situated at the upper edge of the side boards of the container bed.
The tarp can be manually unwound from the roller using a pull rope attached to the pull bar. As the tarp is initially unfurled, the pull bar rides on the side boards of the dump bed until it reaches the position of the load arm yokes. As the bar is pulled further, it lodges within the yokes and is conveyed along an arc defined by the pivoting load arm assemblies. The arc carries the pull bar, and consequently the tarp, above a heaped load within the dump bed. The load arm assemblies swing through their complete arc as the catch again contacts the bed side boards near the opposite end of the bed. At this point, continued movement of the pull bar extracts the bar from the yoke, eventually covering the entire dump bed.
In a preferred embodiment, the load arm assemblies include a pair of telescoping arms. This feature allows the length of each load arm to be adjusted, which thereby adjusts the diameter of the arc through which the tarp is conveyed by the arms. Preferably, the length of each load arm assembly is adjusted to provide adequate clearance between the tarp/pull bar and the heaped load at the zenith of the arc travel of the pivoting load arms. Also preferably, each load arm is pivotably mounted to an upper or top rail of the open top container or load bed, to thereby minimize the length of the telescoping arms needed to clear the heaped load.
Each load arm assembly can be readily installed on an existing container, such as a dump bed. In certain embodiments, a mounting bracket can be bolted to the top rail of the bed. A pivot pin can project from the bracket and through a pivot bore at the base of one of the telescoping arms. A cotter pin can hold the pivoting assembly together. The telescoping arms can be formed by one tubular shaped arm slidably mounted within another larger tubular shaped arm. A nut can be welded onto the outer arm to receive a set screw. As the set screw is threaded into the nut, it passes through the outer arm to provide a frictional clamping force against the inner arm.
The present invention further contemplates a method for conveying a retractable tarp across an open top container, especially over a heaped load within the container. The method comprises unrolling the tarp partially from its roller and conveying the leading edge of the tarp partially across the container bed. Prior to the tarp contacting the heaped load, the leading edge of the tarp is engaged by at least one pivoting arm, mounted to a side of the container bed. Preferably, two such arms are provide on opposite sides of the bed to support the tarp at its side edges.
Next, the tarp is pulled further toward an opposite end of the container bed. As the tarp is pulled, it follows the path of the pivoting arm as it swings through its travel arc. This path conveys the tarp up and over the heaped load. Once the tarp has cleared the load, it can be pulled to the end of the container bed where it can be fastened in its final position covering the open top container.
In another feature of the inventive method, the tarp leading edge can be disengaged from the pivoting arm at the end of the travel arc of the arm. Preferably, the travel arc of the arm spans the length of the heaped load, and most preferably beyond the length of the load to minimize possible contact between the tarp and the load.
It is one object of the invention to provide an apparatus for conveying a flexible cover, such as a tarp, over an open top container. A more specific object resides in features of the inventive system that allow the tarp to be conveyed over a heaped load without being dragged across the load.
One benefit of the inventive system is that it can be used with an existing retractable tarp system mounted on an existing open top container. A further benefit is realized by features of the invention that allow use of as short an arm assembly as necessary to convey the tarp over the heaped load.
A further benefit of the present cover system is that the length of the arms can be easily adjusted with the heaped load within the container bed. Other benefits and additional objects of the invention should become apparent upon consideration of the following written description taken with the accompanying drawings.